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Combination Law for Drude–Sommerfeld's Electron Damping in Multilayer Thin Metal Films
Author(s) -
Mezzasalma Stefano A.,
Janicki Vesna,
Salamon Krešimir,
SanchoParramon Jordi
Publication year - 2018
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201800149
Subject(s) - plasmon , thin film , electron , condensed matter physics , free electron model , drude model , materials science , physics , phenomenology (philosophy) , field (mathematics) , fermi energy , metal , phenomenological model , optics , quantum mechanics , nanotechnology , philosophy , mathematics , epistemology , pure mathematics , metallurgy
A combination rule for electron damping in multilayer thin metal films is derived from a mean‐field picture and is applied to optical experimental data. The overall coefficient obeys a parallel law of pure materials damping,〈 γ 〉 − 1 =g ¯ Aγ A− 1 +g ¯ Bγ B− 1(g ¯i < 1 ) , chemical specificity being involved by averaging over densities of low energy states in the free electron model. Geometric and static electromagnetic features of single layers couple via small Fermi's energy fractions ( α i ). An application is developed for thin Cu/Au and Au/Ag films, showing an apparently irregular damping trend in the film thickness ( d i = 2.5–7.5 nm). The inferred ⟨ γ ⟩'s agree in both cases with our data when | α i | = 10 −2 ÷ 10 −3 linearly increases with decreasing d i , suggesting a coupling phenomenology that can bring new insights in the optics and plasmonics of nanostructures.